cat medals.txt | wc -l
grep -E "中国|中国香港|中国台北" medals.txt | sort -k2nr
sort -k4,4nr -t',' ./medals.txt | head -n 5 | cut -d',' -f1
ort -k2,2nr -t',' ./medals.txt | head -n 5 | awk -F',' '{sum+=$2} END{print "金牌前五总数："sum}'

